Glass-ceramics with a lithium disilicate and an apatite crystal phase are known from the state of the art.
In Cent. Eur. J. Chem, 7(2), 228-233 (2009), M. Palou et al. report on the crystallization of a mixture of pure lithium disilicate glass and fluoroapatite glass. The glass ceramic produced has a high level, 14 wt.-%, of P2O5 and displays bioactivity during in-vitro tests in simulated body fluid.
In Journal of Thermal Analysis and calorimetry 78(1), 73-82 (2004), S. C. Mojumdar et al. describe studies on the crystallization of glasses from the Li2O—CaO—CaF2—P2O5—SiO2 system with various levels of P2O5. After crystallization of a glass with a 15 wt.-% content of P2O5, fluoroapatite was detected in addition to a lithium disilicate crystal phase by means of X-ray diffraction.
However, the lithium silicate glass-ceramics with apatite crystal phase known from the state of the art are bioactive products and not chemically resistant materials which are suitable for restorative dentistry. In body fluids or simulated body fluids, bioactive products form apatite crystals on the surface in order, e.g. in the case of an endoprosthetic implant, to produce a solid bond with the bone.
Therefore, the known glass-ceramics have the serious disadvantage that they do not possess the chemical resistance required for a dental material which comes into contact with a wide variety of fluids in the oral cavity.